Bergey's Manual of Systematic Bacteriology, vol. 2, ed. by Sneath et al., Williams & Wilkins, Baltimore, London, Los Angeles, Sydney, 1984, Part 14, p. 1208 onwards, describes under title “Regular, Nonsporing Gram-Positive Rods” characteristics and classification of microorganisms belonging to the genus Lactobacillus as well as properties of the species Lactobacillus helveticus. Generally, Lactobacillus helveticus strains have been isolated from dairy products, such as fermented milk products and cheeses, and conventionally, they have been used as starter microbes in the manufacture of cheeses, particularly cheeses of Emmental and Gruyère type.
Biological effects of Lactobacillus helveticus strains have also been described in the prior art. For instance, international patent application WO99/16862, Yamamoto et al., describes the strain Lactobacillus helveticus CM4, FERM BP-6060 which is capable of producing a large amount of the tripeptide Val-Pro-Pro and/or Ile-Pro-Pro and which has high extracellular protease activity. The publication also describes fermented milk products containing the above-mentioned tripeptides and bacterium, and a method for the preparation thereof by fermenting products containing the tripeptide sequences with said bacterium.
U.S. Pat. No. 5,449,661, Nakamura et al., describes the preparation of a peptide containing the tripeptide sequence Val-Pro-Pro and its use for lowering hypertension. The peptide is prepared by fermenting fat-free milk with the strain Lactobacillus helveticus JCM 1004, whereafter the peptide is purified chromatographically and freeze-dried.
Yamamoto et al. have also described purification and characterization of a proteinase originating from the microorganism Lactobacillus helveticus CP790 (J. Biochem., 1993, 114:740). Moreover, Yamamoto et al. have also reported on a research in which αs1- and β-casein were hydrolysed with said proteinase and the obtained peptides were studied for their inhibitory effect on ACE (J Dairy Sci, 1994, 77:917). The studied peptides were 25 in total and their molecular sizes and effects differed greatly. The most efficient ones were three peptides obtained from β-casein and containing 8, 18 and 27 amino acids respectively. The study also compared ACE-activity of milk fermented with the strain Lactobacillus helveticus CP790 and its variant CP791 with defective proteinase activity, whereby the former was found effective in spontaneously hypertensive SHR rats but not in an ordinary rat strain, whereas the latter had no activity at all.
Even though lactic acid bacteria and also the species Lactobacillus helveticus have been widely studied and recommended for use both as a conventional starter and as a health-promoting substance, there is still a constant pursuit in the field of finding new, effective microbes which are useful both as starters and as probiotics in dairy and other food industries as well as natural products and also in pharmaceutical industry.